This invention relates to pneumatic tires and in particular to a radial ply pneumatic tire having overall improved high speed operating characteristics.
There are currently three basic types of pneumatic tires available to the motoring public. The first is the bias ply tire in which the reinforcing cords in the plies in the body of the tire extend diagonally from bead to bead across the tire structure and the cords in each ply are usually crossed with respect to the cords in adjacent plies.
The second basic type of tire is the bias belted tire which is similar to the bias tire but includes a belt structure. The belt structure is one or more layers of reinforcing material which extend circumferentially about the tire and beneath the tread portion and terminates in axial directions at approximately beneath the outer edges of the tread portion. This belt structure serves to restrict the outer circumference of the tire and provides a more rigid tread portion.
The third basic tire construction is the radial ply tire. This tire is characterized by the cords in the body plies extending from bead to bead in radial directions. In other words, the cords in the body plies lie substantially in planes containing the rotational axis of the tire. The radial ply tire further includes a very strong tension resistant belt structure which extends circumferentially about the carcass and is disposed beneath the tread portion. The belt structure again generally terminates in axially outer directions at approximately beneath the outer edges of the ground contacting surface of the tread.
The radial ply tire has increased in popularity in recent years possibly because of its increased tread wear capability, improved skid resistance, capability of developing high cornering forces to resist lateral forces which develop in turns, and its soft riding qualities generally attributable to its soft flexible sidewalls. Even in view of these many improved characteristics of the radial ply tire over the previous bias and bias belted tire, engineers are constantly attempting to gain further improvements in these capabilities in the tires in order to provide the best possible products for the consuming public.